Effectiveness of Twin-Beam Dual-Energy Computed Tomography in Characterization of Solitary Pulmonary Nodules Larger Than 5 Mm

Abstract

Background: Advancements in technology have significantly improved the diagnosis of solitary pulmonary nodules in thelungs. Various computed tomography (CT) imaging techniques, including modern dual-energy computed tomography (DECT),have enhanced the ability to accurately classify pulmonary nodules as benign or malignant. In this study, three different dual-energy parameters - iodine load, contrast load, and visual assessment - were evaluated for their potential in characterizingpulmonary nodules. Objectives: The aim of this study was to assess the reliability and effectiveness of DECT in distinguishing benign frommalignant pulmonary nodules using different parameters, including visual assessment, iodine concentration, and contrastload. Patients and Methods: This prospective study included patients who underwent contrast-enhanced thoracic DECT forsolitary pulmonary nodules, had histopathological examination results, or had at least a two-year follow-up CT scan. Patientswith nodules smaller than 6 mm or completely calcified nodules were excluded. Patients diagnosed with a suspicious solitarypulmonary nodule on chest radiography and subsequently underwent contrast-enhanced DECT, or those diagnosed with a lungnodule on routine non-contrast CT scans and later evaluated using DECT, were included in the study. Benign and malignantnodules were compared based on gender, age, contrast load, iodine load, and color map assessment. Nodule images wereobtained 40 seconds after intravenous contrast administration using single-source DECT (120 kV split filter) with twin-beamtechnology. The visual enhancement and color map evaluation, including contrast and iodine load measurements, wereseparately calculated and recorded for each lung nodule. Results: A total of 59 patients [30 males (50.8%) and 29 females (49.2%)] with a solitary pulmonary nodule met the inclusioncriteria. Among the 59 pulmonary nodules, 16 (27.1%) were malignant, and 43 (72.9%) were benign. Of the benign lesions, 23(53.5%) were found in males and 20 (46.5%) in females. The mean age of patients with benign nodules was 53.5 +/- 12 years (range:25 - 73 years), while for those with malignant nodules, it was 69.2 +/- 5.59 years (range: 57 - 75 years). There was no statisticallysignificant difference in age between the two groups (P = 0.506). The median contrast load was 0.0 Hounsfield units (HU)[interquartile range (IQR: 64)] in benign nodules and 63 HU (IQR: 154) in malignant nodules. Malignant nodules had asignificantly higher contrast load than benign nodules (P = 0.003). Using a cut-off value of 22 HU for contrast load in malignancydiagnosis, the sensitivity was 100%, specificity was 58.14%, positive predictive value (PPV) was 47.06%, and negative predictivevalue (NPV) was 100%. The area under the curve (AUC) was 0.746. The median iodine load was 0.0 mg/dL (IQR: 4.5) in benignnodules and 4.5 mg/dL (IQR: 11.8) in malignant nodules. Malignant nodules had a significantly higher iodine load than benignnodules (P < 0.001). Using a cut-off value of 1 mg/mL for malignancy diagnosis, the sensitivity was 100%, specificity was 62.79%,PPV was 50%, and NPV was 100% (AUC: 0.768). Conclusion: Dual-energy computed tomography provides valuable contributions in differentiating benign and malignantpulmonary nodules. In this study, the diagnostic value of three different approaches - visual iodine coverage color map, iodineconcentration, and contrast load - was demonstrated in distinguishing these lesions.